[EXPERIMENT] The best temperature to create fermented rice

Put simply, fermented rice is made by steaming the rice, adding yeast & sugar or koji to it so that it ferments. Apparently the temperature the rice is at when the koji is added affects the way the rice eventually ferments, if the temperature is not right then the rice will end up too sour or go off. So, what is the best temperature for fermented rice to be created? Does the temperature affect the fermenting of the rice?

INDEPENDENT VARIABLES: The temperature at which the fermented rice is made. (Cooler or warmer conditions)

DEPENDENT VARIABLE: How well the rice ferments. (Is it too sour? Did it go off? etc.)

CONTROLLED VARIABLE: The brand of koji used, the brand of rice, the type of rice, the type of bowl the rice is left in, the steaming time for the rice, the mixing time, the amount of koji used, the amount of rice used,